1. Field of the Invention
The present invention relates to a cooling system of a stationary blade of a gas turbine, in particular, a cooling system of a stationary blade having superior cooling efficiency, and to a gas turbine.
2. Description of Related Art
A gas turbine used for a generator and the like is shown in FIG. 4.
Compressor 1, combustor 2, and turbine 3 are shown in FIG. 4, and rotor 4 extends from compressor 1 to turbine 3 in the axial direction.
Inner housing 6, and cylinders 7 and 8 provided at the compressor 1 side enclose the outside of compressor 1. Furthermore, cylindrical shell 9 forming chamber 14, outside shell 10 of turbine 3, and inside shell 11 are provided in the gas turbine.
Inside of cylinder 8 which is provided in compressor 1, stationary blades 12 are disposed in the circumferential direction at equal intervals. Moving blades 13, which are disposed around rotor 4 at equal intervals, are disposed between stationary blades 12.
Combustor 15 is disposed in chamber 14 which is enclosed by cylindrical shell 9. Fuel supplied from fuel feeding pipe 35 is injected from fuel injection nozzle 34 into combustor 15 to burn.
A high temperature combustion gas generated in combustor 15 is introduced into turbine 3 while passing through duct 16.
In turbine 3, two-stage type stationary blades 17, which are disposed in the circumferential direction at equal intervals on inside shell 11, and moving blades 18, which are disposed in the circumferential direction at equal intervals on rotor 4, are alternately provided in the axial direction. The high temperature combustion gas is fed into turbine 3 and is discharged as an expanded gas, and further, the high temperature combustion gas rotates rotor 4 on which moving blades 18 are fixed.
Manifolds 21 and 22 are provided in compressor 1 and turbine 3 respectively. Manifolds 21 and 22 are connected with each other by air piping 32, and cooling air is supplied from the compressor 1 side to the turbine 3 side via air piping 32.
A portion of cooling air from compressor 1 is supplied from a rotor disc to moving blades 18 in order to cool moving blades 18. As shown in FIG. 4, a portion of cooling air from manifold 21 of compressor 1 passes through air piping 32 and is introduced into manifold 22 of turbine 3 to cool stationary blades 17, and simultaneously, the cooling air is supplied as sealing air.
Next, a structure of stationary blades 17 will be explained below.
In FIG. 5, inner shroud 26 and outer shroud 27 are provided at the inside and the outside of blade 25 respectively.
Inside of blade 25, leading edge path 42 and trailing edge path 44 are formed by rib 40. Cylindrical insert parts 46 and 47, in which plural cooling air holes 70, 71, 72, and 73 are formed at the peripheral surfaces and bottom surfaces, are inserted from the outer shroud 27 side into the leading edge path 42 and trailing edge path 44.
Blade 25 is equipped with pin fin cooling part 29 comprising a flow path having plural pins 62 at the trailing edge side.
When cooling air is supplied from manifold 22 into insert parts 46 and 47, the cooling air is ejected from cooling air holes 70, 71, 72, and 73, and hits the inner walls of leading edge path 42 and trailing edge path 44 to carry out so-called impingement cooling. Furthermore, the cooling air flows through pin fin cooling part 29 comprising flow paths formed between plural pins 62 at the trailing edge side of blade 25 to carry out pin fin cooling.
On inner shroud 26, forward flange 81 and rearward flange 82 are formed at the leading edge side and the trailing edge side, and are connected to seal supporting part 66, which supports seal 33 for sealing arm 48 of rotor 4 and seal supporting part 66. Furthermore, cavity 45 is formed between seal supporting part 66 and inner shroud 26. The cooling air ejected from cooling air holes 70, 71, 72, and 73 of insert parts 46 and 47 is supplied into cavity 45.
Flow path 85 is formed at the forward side of seal supporting part 66. Air is injected from cavity 45 while passing through flow path 85 toward the front stage moving blade 18 and toward the rear stage moving blade while passing through spaces formed in seal 33, and the inside is maintained at a pressure higher than that of a path of high temperature combustion gas in order to prevent high temperature combustion gas from penetrating to the inside.
As shown in FIGS. 6 and 7, leading edge flow path 88 equipped with plural needle fins 89 is formed at the leading edge side of inner shroud 26. Leading edge flow path 88 is connected to cavity 45 via flow path 90. Rails 96 are formed along the leading edge toward the trailing edge at both sides of inner shroud 26. In each rail 96, flow path 93 is formed in which one end of each rail 96 is connected to leading edge flow path 88 and the other end of each rail 96 opens at the trailing edge of inner shroud 26.
On the bottom surface of inner shroud 26, collision plates 84 having plural small holes 101 are provided at an interval from the bottom surface. By providing these collision plates 84, chamber 78 is formed at the bottom surface side of inner shroud 26.
Furthermore, at the trailing edge side of inner shroud 26, plural flow paths 92 are formed so as to be connected to the trailing edge of inner shroud 26 and chamber 78.
Cooling air flowing into cavity 45 is injected into leading edge flow path 88 of inner shroud 26 via flow path 90, passes through the space between needle fins 89 to cool the leading edge side of inner shroud 26, and subsequently passes through side flow path 93 to be ejected from the trailing edge of inner shroud 26.
Moreover, cooling air flowing into cavity 45 flows into chamber 78 from small holes 101 and passes through flow path 92 to be ejected from the trailing edge of inner shroud 26. When cooling air flows into chamber 78 from small holes 101 of collision plate 84, cooling air hits the bottom surface of inner shroud 26, carrying out impingement cooling. Due to impingement cooling, cooling air passes through plural flow paths 92 to cool the trailing edge side of inner shroud 26.
As shown in FIG. 8, collision plates 102 having plural small holes 100 are provided at the upper surface of outer shroud 27 at an interval from the upper surface. By providing these collision plates 102, chamber 104 (not shown) is formed at the upper surface side of outer shroud 27.
Leading edge flow path 105 is formed in outer shroud 27, and side flow path 106, which opens at the trailing edge of outer shroud 27, is formed at both sides thereof. Leading edge flow path 105 is connected to one chamber 104.
Furthermore, at the trailing edge side of outer shroud 27, plural flow paths 107 are formed so as to be connected to the trailing edge of outer shroud 27 and chamber 104.
Cooling air flowing into manifold 22 flows into chamber 104 from small holes 100 of collision plate 102 and passes through trailing edge flow path 107 to be ejected from the trailing edge of outer shroud 27. When cooling air flows into chamber 104 from small holes 100 of collision plate 102, cooling air hits the upper surface of outer shroud 27, carrying out impingement cooling.
Furthermore, cooling air flowing into chamber 104 flows into leading edge flow path 105 and passes through leading edge flow path 105 and side flow paths 106 to cool the leading edge and both sides of outer shroud 27. Subsequently, cooling air is ejected from the trailing edge of outer shroud 27.
As described above, in stationary blades of this type of gas turbine, the blade metal temperature is maintained at an allowable temperature or less using various cooling techniques, such as impingement cooling, and pin fin cooling by introducing a portion of compressed air. However, inner shroud 26 and outer shroud 27 require a large amount of air for cooling of the trailing edge side. As a result, further improvement of cooling efficiency is required.
The present invention is conceived in view of the above-described problems and has an object of the provision of a cooling structure of a stationary blade in which the amount of cooling air is reduced to be used while significantly improving cooling efficiency, and of the provision of a gas turbine.
In order to solve the problems, a first aspect of the present invention is to provide a cooling structure of a stationary blade comprising an inner shroud and an outer shroud at the inside and outside of a blade, in which the outer shroud, the blade, and the inner shroud are cooled by cooling air to be sent to the outer shroud side. A cavity is formed at an inner surface of the inner shroud into which cooling air passing through the blade is sent. The inner shroud comprises: a collision plate having plural small holes which is provided at an interval from the bottom surface to form a chamber between the bottom surface and the collision plate, for guiding the cooling air in the cavity from the small holes into the chamber; a leading edge flow path provided at a leading edge side along a width direction for guiding the cooling air in the chamber; a side flow path provided along both sides for guiding the cooling air in the leading edge flow path to a trailing edge side; a header formed along the width direction near the trailing edge for feeding the cooling air from the side flow path; and plural trailing edge flow paths formed at intervals along the width direction at the trailing edge side, each having one end connected to the header and the other end being open at the trailing edge, for ejecting the cooling air in the header from the trailing edge.
In the above-described cooling structure of a stationary blade, the outer shroud may comprise: a collision plate having plural small holes which is provided at an upper surface of the outer shroud at an interval to form a chamber between the upper surface and the collision plate; a leading edge flow path provided at a leading edge side along a width direction for guiding cooling air in the chamber; a side flow path provided along both sides for guiding the cooling air in the leading edge flow path to a trailing edge side; a header formed along the width direction near the trailing edge for feeding the cooling air from the side flow path; and plural trailing edge flow paths formed at intervals along the width direction at the trailing edge side, each having one end connected to the header and the other end being open at the trailing edge, for ejecting the cooling air in the header from the trailing edge.
In the above outer shroud, plural trailing edge flow paths may be provided along the width direction at predetermined intervals.
Furthermore, a second aspect of the present invention is to provide a cooling structure of a stationary blade comprising an inner shroud and an outer shroud at the inside and outside of a blade, in which the outer shroud, the blade, and the inner shroud are cooled by cooling air to be sent to the outer shroud side. The outer shroud comprises: a collision plate having plural small holes which is provided at an interval from the upper surface to form a chamber between the upper surface and the collision plate, for guiding the cooling air from the small holes into the chamber; a leading edge flow path provided at a leading edge side along a width direction for guiding the cooling air in the chamber; a side flow path provided along both sides for guiding the cooling air in the leading edge flow path to a trailing edge side; a header formed along the width direction near the trailing edge for feeding the cooling air from the side flow path; and plural trailing edge flow paths formed at intervals along the width direction at the trailing edge side, each having one end connected to the header and the other end being open at the trailing edge, for ejecting the cooling air in the header from the trailing edge.
In the above-described cooling structure of a stationary blade, plural trailing edge flow paths may be provided along the width direction of the outer shroud at predetermined intervals.
According to the above-described cooling structure of a stationary blade, the stationary blade is cooled by allowing the cooling air from the small holes of the collision plate to flow into the chamber, passing the cooling air after being used for the impingement cooling through the leading edge side and both sides, and sending the cooling air to the trailing edge side. Therefore, in comparison with the effects of a conventional cooling structure in which the cooling air after being used for the impingement cooling is simply sent to the trailing edge side and is ejected, the amount of the consumed cooling air is largely reduced and therefore, the cooling efficiency is significantly improved.
Furthermore, the present invention provides a gas turbine having a cooling structure of a stationary blade according to any one of the above-described structures, wherein a stationary blade constitutes a turbine which rotates a rotor by means of combustion gas from a combustor.
As described above, since the gas turbine has a stationary blade having superior cooling efficiency, the amount of the consumed cooling air is largely reduced and the performance of the gas turbine is improved.